Parathyrin and calcium homeostasis in the fetus.
The response of plasma parathyrin (PT) in cattle fetuses to changes in plasma calcium was investigated in utero. Resting plasma calcium levels for 4 fetuses averaged 3.1 mg/dl higher than for their mothers. Fetal PT levels (0.67 ng/ml) were half those of the mother (1.40 ng/ml). Hypocalcemia induced by EDTA infusion evoked a rise in plasma PT in 2 or 3 fetuses. The relationship between plasma PT and calcium levels in these fetuses was curvilinear, PT rising from about 0.7 ng/ml at 13 mg calcium/dl to a plateau of about 1.6 ng/ml below 10 mg calcium/dl. This contrasted with one of the mothers in which PT rose above 3 ng/ml when plasma calcium fell from 9 to 7 mg/dl. During infusion of EDTA to mother or fetus there were no changes in plasma calcium or PT levels in the respective fetus or mother.
D000818:Animals; D002118:Calcium / Q000097:blood*; D002417:Cattle / Q000196:embryology*; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D005312:Fetal Blood / Q000378:metabolism*; D006706:Homeostasis; D007700:Kinetics; D008431:Maternal-Fetal Exchange; D010281:Parathyroid Hormone / Q000097:blood*; D011247:Pregnancy
D010281:Parathyroid Hormone; D004492:Edetic Acid; D002118:Calcium